Breast cancer and second primary ovarian cancer in dermatomyositis.

We report six female patients with breast cancer who developed dermatomyositis and compare our data with those from other reports. The development of dermatomyositis in two patients led to the discovery of a second primary ovarian carcinoma, whereas the development of dermatomyositis in another two patients led to the discovery of recurrent breast cancer. In three patients the diagnosis of dermatomyositis preceded the diagnosis of breast cancer, while the rest developed dermatomyositis after the diagnosis of breast cancer. A parallel clinical course of dermatomyositis and breast cancer was seen in only one patient. Coexisting dermatomyositis and breast cancer is a rare phenomenon, and dermatomyositis that develops during the course of breast cancer may indicate the occurrence of a second primary malignancy or recurrent breast cancer. The onset of dermatomyositis may precede, coincide with, or follow the diagnosis of breast cancer. The clinical course of dermatomyositis sometimes, but not always, parallels the course of breast cancer. There are no specific clinical or laboratory markers to distinguish patients with dermatomyositis who have malignancy from those without cancer.